Continuous casting apparatuses of the twin-roll type for casting a thin steel plate have been known in which a pair of mold rolls are employed for drawing slabs through a clearance between the rolls. In such twin-roll type continuous casting apparatus, side weirs are provided at opposite ends of the rolls so as to form a molten metal (molten steel) reservoir above the gap between the two rolls. The side weirs are pressed against the rolls under considerable force in order to prevent any leakage of molten metal.
However, such known arrangement involves a problem that abrasive wear occurs between the rolls and the side weirs with the result that the service life of the side weirs is reduced and that corner portions of the rolls become rounded, the sealing performance of the arrangement being thus adversely affected. Another problem is that both the rolls and the side weirs are inevitably thermally affected so that some gap is produced in the interface between each roll and each side weir, with the result that molten metal enters the gap to produce burrs which would be a cause of inferior slab configuration or breakage of slide portions of the side weir, thus leading to a shutdown in casting operation.